Let me answer the last part first. You don't become resistant, the germs do. When germs are bathed in an antibiotic environment they have the ability to evolve and become resistant. It goes something like this: Suppose you present a germ killing antibiotic to a large population of bacteria. Normally this antibiotic is known to be effective against these germs. Perhaps the antibiotic kills one million bacteria, but there is one that is left behind. A random gene mutation has occurred in that one bacteria which protects it from the germ killing properties of the antibiotic. That resistant germ then goes on to reproduce and create a whole population of "super bugs" which are resistant to the previously effective drug. One theory which is bandied about is that partial treatment of the germ population makes this more likely to occur. In other words, if you kill 90% of the bacteria present then the surviving 10% are more likely to posses some relative genetic protection which can be refined as this group continues to reproduce. Bacteria do not share pieces of DNA so this theory seems improbable to me. The theory goes on to suggest that continuous antibiotic pressure against the germ population doesn't leave any stragglers behind who can then mutate and become resistance. Again, this theory doesn't make any logical sense. The truth is that antibiotics do in fact makeit more likely that resistant bacteria will emerge.But there are other important issues you need to keep in mind. Germs can only become resistant if you are infected with them. If you do not have a Staph infection then you cannot become a factory for MRSA. These mutations primarily occur in hospitals because that is where you find lots of sick people who are infected with things like Staph. You have to weigh the theoretical good of society against the needs that you have as an individual. We don't know for sure that you taking antibiotics will increase the population of resistant germs in the community; but we sure as hell know that you need the antibiotics and that you will probably become sicker without them. If you don't need them you shouldn't be taking them.
Borrellia burdorferei, the bug that causes Lyme is a nasty critter. A lot of science has been done to prove how hard it is to exterminate. It can change it outer proteins to fool your immune system. It can acquire host proteins and display them on its surface to camouflage itself from you immune system. It sequesters itself in hard to get at places. It morphs into three different forms. It widely disseminates to many tissues throughout your body. It changes your body's chemistry in ways that subvert your immune responses, as will be discussed later. Animal studies prove that dogs who have been treated with huge doses of antibiotics still have the spirochetes in their systems. Patients who have gotten better after long courses of antibiotics frequently relapse soon after the antibiotics are stopped. And they start getting better when the antibiotics are started up again. ILADS reports that chronic Lyme patients require antibiotics for one to four years. Dr. Jones, the 81 year old pediatric authority on Lyme reports that his patients have required treatement for three to seven years. Here is the rub. It is very hard to cure. Still, many of my patients get better in 4 to 9 months. I have one patient in my practice who has been on antibiotics for 12 years, he is stable but unfortunately his Lyme is still quite active. I don't know any doctors who want to prescribe long term antibiotics. We just want to make our patients better, symptom free without relapse. And we are willing to do whatever is necessary. That is why we became doctors.